5 Infections That Cause Birth Defects

Infection is a major cause of birth defects

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Infection during pregnancy is a major cause of birth defects. Infections that would typically result in no or mild symptoms in an adult can have severe consequences for the unborn baby. When such infection doesn’t result in loss of pregnancy or stillbirth, it can lead to low birth weight and dysfunction of multiple organ systems in the baby.

Early detection of infection during pregnancy is of cardinal importance. Screening for infection results in reducing the prevalence of intrauterine infection and birth defects. Certain steps can be taken to minimize the risk of infection during pregnancy, including vaccination and preventive measures.

It’s important that all women who are either pregnant or planning on becoming pregnant be aware of the various pathogens that can result in pregnancy loss or birth defects.

Cytomegalovirus Infection

Cytomegalovirus (CMV) infection is the most common infection present at birth (i.e., congenital infection) in the United States. Infection with CMV during pregnancy increases the risk that the baby will experience congenital CMV.

Most children infected with CMV at birth have no symptoms. Some newborns, however, develop congenital CMV. Symptoms of congenital CMV include the following:

  • inflammation of the retina
  • rash present at birth
  • abnormally small head along with incomplete development of the brain (i.e., microcephaly)
  • yellowing of the skin, eyes, and mucus membranes (i.e., jaundice)
  • enlargement of the liver and spleen
  • low birth weight
  • seizures
  • deposits of minerals in the brain

Most infants with symptoms of infection at birth will have long-term neurological problems, such as hearing loss, vision loss, intelligence disorders, developmental disorders, and so forth. It may take years for these problems to manifest. Furthermore, congenital CMV infection increases the risk of diabetes, thyroid disease, osteoporosis, and so forth. Infants who are infected with CMV at birth but show no symptoms are at much lower risk of such problems.

It’s hard to predict which babies will experience severe congenital CVM. Furthermore, there is no cure for CMV. Treatment plans involve physical therapy, appropriate education, and so forth. In infants with congenital CMV, treatment with antiviral medications may mitigate loss of hearing later in life.

Cytomegalovirus is ubiquitous in the environment; thus, it can be hard to avoid. Nevertheless, pregnant women are advised to limit their interactions with very young children who can spread infection. Specific guidance includes the following:

  • wash hands thoroughly after contact with children’s saliva or diapers
  • avoid kissing children younger than 6 years old on the cheek or mouth
  • avoid sharing food and drink with young children

Additionally, pregnant women who work as daycare providers should avoid contact with children younger than 30 months old.

Rubella Virus Infection

Infection with the rubella virus during pregnancy—particularly during the first trimester—is very serious. Common complications include miscarriage, premature delivery, and death of the fetus. In those babies who are born alive, a condition called congenital rubella syndrome can result.

Congenital rubella syndrome leads to eye, ear, and heart defects as well as microcephaly, or an abnormally small head along with incomplete development of the brain, autism, and mental and motor delay. These issues are permanent.

Notably, results from a 2011 study published in BMC Public Health suggest that between 2001 and 2010, 16,600 cases of congenital rubella syndrome were prevented by rubella vaccination. Furthermore, 1228 cases of autism spectrum disorder were prevented by rubella vaccination during this time period.

Transient or temporary deficits include enlargement of the liver and spleen, skin and bleeding issues (i.e., “blueberry muffin syndrome”), and brain infection.

During prenatal care, a woman should be tested for rubella immunity. Women who are pregnant but not immune to the rubella virus need to be vaccinated after pregnancy. Those who are infected with the rubella virus during pregnancy must be closely monitored. Women who are infected with the rubella virus during the first 11 weeks of pregnancy have an up to 90 percent chance of delivering a baby with congenital rubella syndrome; whereas during the first 20 weeks, the rate drops to 20 percent.

Herpesvirus Infection

Herpes infection during pregnancy can be very severe for the newborn. It can result in pregnancy loss, prematurity, and low birth weight. Herpesvirus infection of the newborn is most serious towards the end of pregnancy, during birth, or immediately following birth. Infection toward the end of pregnancy can result in microcephaly, inflammation of the retina, rash, and hydrocephalus.

According to the NIH, the term hydrocephalus is derived from the Greek words ‘hydro’ meaning water and ‘cephalus’ meaning head. As the name implies, it is a condition in which the primary characteristic is the excessive accumulation of fluid in the brain. Although hydrocephalus was once known as ‘water on the brain,’ the ‘water’ is actually cerebrospinal fluid (CSF) — a clear fluid that surrounds the brain and spinal cord. The excessive accumulation of CSF results in an abnormal widening of spaces in the brain called ventricles. This widening creates potentially harmful pressure on the tissues of the brain.

Infection with herpes during birth or shortly thereafter can result in disease of the eye, mouth, or skin as well as brain and other types of infection.

The risk of such devastating consequences of herpes virus infection can be mitigated by the administration of acyclovir, an antiviral drug, during the final four weeks of pregnancy in a woman who experienced a first episode of genital herpes during pregnancy.

Toxoplasmosis Infection

According to the CDC, toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii. In the United States, it is estimated that 11% of the population 6 years and older have been infected with Toxoplasma. In various places throughout the world, it has been shown that up to 95% of some populations have been infected with Toxoplasma. Infection is often highest in areas of the world that have hot, humid climates and lower altitudes.

Toxoplasma gondii is a parasitic infection mostly spread by cats. Cats become infected by eating rodents and birds that are infected with this parasite.

If you’re pregnant and have a cat, it’s important to avoid changing the kitty litter. Toxoplasmosis is passed through feces. Other guidance includes keeping your cats indoors and feeding them commercial foods.

Other sources of toxoplasmosis include uncooked or partially cooked meat as well as soil and contaminated water. Remember to cook your meat fully at a hot enough temperature. On a related note, wash your hands completely after touching uncooked meat and wash all utensils and dishware used to prepare the meat. Finally, avoid drinking untreated water and wear gloves while gardening.

Women who are infected with toxoplamosis during pregnancy or right before pregnancy can pass infection to the baby. Most infected mothers have no symptoms of infection, and most babies who are infected are usually symptom-free, too. However, infection with toxoplasmosis can result in miscarriage or stillbirth as well as serious birth defects, including hydrocephalus, microcephaly, intellectual disability, and inflammation of the retina.

Typically, the earlier that a mother is infected with toxoplasmosis during pregnancy, the more difficult the resulting illness.

With respect to toxoplasmosis infection in the newborn, the following factors are associated with long-term disability:

  • delays in diagnosis
  • delays in commencement of therapy
  • low blood sugars (i.e., hypoglycemia)
  • oxygen deficiency (i.e., hypoxia)
  • profound vision problems
  • a rise in pressure around the brain (i.e., increased intracranial pressure)
  • untreated hydrocephalus

Up to 70 percent of newborns who receive appropriate and prompt treatment with the medications pyrimethamine and folinic acid develop normally. Treatment should continue during the first year of life.

Zika Virus

Zika is spread by the Aedes mosquito which bites during the day. It can also be spread by unprotected sexual intercourse with an infected partner. Although Zika has been spread locally in both Florida and southern Texas, the preponderance of the current Zika outbreak is occurring in Central America, South America, and the Caribbean.

Zika virus that is passed from the mother to fetus can cause severe birth defects, including microcephaly and brain abnormalities. The risk of these birth defects is 20 times higher in women with Zika virus.

Although work on a Zika vaccine is currently being undertaken, there is no cure or specific treatment for Zika virus. Pregnant women are advised to use bug repellant, avoid travel to areas where Zika is spread, and avoid unprotected intercourse with a partner who could be infected with the virus.

A Word From Verywell

In unborn babies, certain types of infection can lead to birth defects, prematurity, and death.

It’s important that women thinking about becoming pregnant receive the measles-mumps-rubella (MMR) vaccine 3 months before conception . In those who don’t receive the MMR vaccine before conception, it’s important that they receive it immediately after becoming pregnant. Furthermore, vaccinations against influenza, tetanus, diphtheria, and pertussis are all safe during pregnancy and are also recommended.

Women infected with the herpes virus during pregnancy should receive treatment with acyclovir, an antiviral agent, during the final 4 weeks of pregnancy. Doing so will mitigate the risk of birth defects as well as other disease and infection acquired after birth.

Although it may be difficult to prevent cytomegalovirus infection during pregnancy, steps can be taken by a pregnant woman to avoid contact with very young children.

To minimize the risk of toxoplasmosis infection, pregnant women should avoid contact with kitty litter and cat feces.

Finally, pregnant women should avoid traveling to areas where the Zika virus is transmitted, and if they already live in such areas use bug repellant among other preventive measures.

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9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Silasi M, Cardenas I, Kwon JY, Racicot K, Aldo P, Mor G. Viral infections during pregnancyAm J Reprod Immunol. 2015;73(3):199–213. doi:10.1111/aji.12355

  2. National Collaborating Centre for Women's and Children's Health (UK). Screening for infections. Antenatal Care: Routine Care for the Healthy Pregnant Woman. Published 2008.

  3. Ross SA, Novak Z, Pati S, Boppana SB. Overview of the diagnosis of cytomegalovirus infectionInfect Disord Drug Targets. 2011;11(5):466–474.

  4. Bouthry E, Picone O, Hamdi G, Grangeot-keros L, Ayoubi JM, Vauloup-fellous C. Rubella and pregnancy: diagnosis, management and outcomes. Prenat Diagn. 2014;34(13):1246-53.

  5. Straface G, Selmin A, Zanardo V, De Santis M, Ercoli A, Scambia G. Herpes simplex virus infection in pregnancyInfect Dis Obstet Gynecol. 2012;2012:385697. doi:10.1155/2012/385697

  6. Hydrocephalus Fact Sheet. National Institute of Neurological Disorders and Stroke. Published 2013.

  7. CDC - Toxoplasmosis - Epidemiology & Risk Factors. Centers for Disease Control and Prevention. Published April 4, 2018.

  8. Fitzgerald B, Boyle C, Honein MA. Birth Defects Potentially Related to Zika Virus Infection During Pregnancy in the United StatesJAMA. 2018;319(12):1195–1196. doi:10.1001/jama.2018.0126

  9. White SJ, Boldt KL, Holditch SJ, Poland GA, Jacobson RM. Measles, mumps, and rubella. Clin Obstet Gynecol. 2012;55(2):550-9.

Additional Reading
  • Barbieri RL, Repke JT. Medical Disorders During Pregnancy. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill; 2014.
  • Berger, BE, Navar-Boggan, AM, Omer, SB. Congenital rubella syndrome and autism spectrum disorder prevented by rubella vaccination--United States, 2001-2010. BMC Public Health. 2011;11:340.
  • Kim K, Kasper LH. Toxoplasma Infections. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill; 2014.
  • Levin MJ, Asturias EJ, Weinberg A. Infections: Viral & Rickettsial. In: Hay WW, Jr., Levin MJ, Deterding RR, Abzug MJ. eds. CURRENT Diagnosis & Treatment Pediatrics, 23e New York, NY: McGraw-Hill; .
  • Rudnick, CM, Hoekzema, GS. Neonatal Herpes Simplex Virus Infections. American Family Physician. 2002; 65(6):1138-1142.
  • Zheng, X, et al. Intrauterine Infections and Birth Defects. Biomedical and Environmental Sciences. 2004; 17:476-491.